Here's what I found out on this problem. It's not just a couple of random photos not showing up in albums. It's every photo with photoID starting with 0 that is not showing up. I mean, it's the whole first million of photos! Only the latest 400 000 photos are visible in albums. But I hope the A.net crew is already looking into this issue and soon everyting will be back to normal.

What else I've noticed, when I open an album from my profile page, every album opens at "photos and info" setting regardless what it is actually set to (such as "photos only", etc.). I hope this will be fixed, too.

And another one problem: on the profile page now only the album's name is displayed, but not the comment (bottom line of the album's name). This I find rather frustrating, as some of the album's names can look meaningless without seeing their bottom line (aka comment).